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<a href="cong__ctl__util_8hpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright 2023 Akamai Technologies, Inc.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> *</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> * Licensed under the Apache License, Version 2.0 (the</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * &quot;License&quot;); you may not use this file except in</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> * compliance with the License.  You may obtain a copy</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * of the License at</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> *</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> *   https://www.apache.org/licenses/LICENSE-2.0</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> *</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * Unless required by applicable law or agreed to in</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * writing, software distributed under the License is</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> * distributed on an &quot;AS IS&quot; BASIS, WITHOUT WARRANTIES OR</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * CONDITIONS OF ANY KIND, either express or implied.</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * See the License for the specific language governing</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> * permissions and limitations under the License. */</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"></span> </div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"></span><span class="preprocessor">#pragma once</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span> </div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="preprocessor">#include &quot;<a class="code" href="detail_2net__flow__fwd_8hpp.html">flow/net_flow/detail/net_flow_fwd.hpp</a>&quot;</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="preprocessor">#include &quot;<a class="code" href="peer__socket_8hpp.html">flow/net_flow/peer_socket.hpp</a>&quot;</span></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span><span class="preprocessor">#include &lt;boost/weak_ptr.hpp&gt;</span></div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="preprocessor">#include &lt;string&gt;</span></div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span> </div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceflow_1_1net__flow.html">flow::net_flow</a></div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span>{</div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span><span class="comment">// Types.</span></div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span><span class="comment"></span> </div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="comment">/**</span></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span><span class="comment"> * Utility class for use by Congestion_control_strategy implementations that implements congestion</span></div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span><span class="comment"> * window and slow start threshold storage and classic Reno-style &quot;slow start&quot; and &quot;congestion</span></div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span><span class="comment"> * avoidance&quot; algorithms.</span></div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span><span class="comment"> *</span></div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span><span class="comment"> * While all (most?) congestion control algorithms store a CWND value, how each one computes or stores it is</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment"> * entirely up to the particular implementation.  Thus each Congestion_control_strategy subclass can</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment"> * just store its own CWND data member, possibly an SSTHRESH data member, and re-implement slow</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span><span class="comment"> * start and congestion avoidance as needed.</span></div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span><span class="comment"> *</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span><span class="comment"> * However, many (most?) congestion control algorithms use the classic TCP congestion control (Reno)</span></div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span><span class="comment"> * slow start and congestion avoidance algorithms.  That is, upon acknowledgment, CWND increases</span></div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span><span class="comment"> * either linearly (if CWND &gt;= SSTRESH) or exponentially (CWND &lt; SSTHRESH); these are &quot;congestion</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="comment"> * avoidance&quot; and &quot;slow start&quot; modes respectively.  Where most (all?) Reno-based algorithms (e.g.,</span></div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span><span class="comment"> * Westwood+) differ is what they do to CWND when loss is detected; they may halve SSTHRESH and CWND</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span><span class="comment"> * or do some other thing.  However, in almost all cases, at least in some situations CWND grows</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span><span class="comment"> * according to either SS or CA based on SSTHRESH.  Therefore, for code reuse among the various</span></div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span><span class="comment"> * Congestion_control_strategy implementations, this class stores CWND and SSTHRESH, increases the</span></div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span><span class="comment"> * former when asked to (based on CWND vs. SSTHRESH), and sets SSTHRESH and CWND to arbitrary given</span></div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span><span class="comment"> * values when asked to.</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span><span class="comment"> *</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span><span class="comment"> * The Linux TCP implementation is kind of based on the same idea, wherein a Reno-style `struct` storing CWND,</span></div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="comment"> * SSTHRESH, and acked-bytes-so-far values also has a pointer to a &quot;polymorphic&quot; `struct` corresponding to the</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="comment"> * custom congestion control implementation (e.g., a Westwood-specific `struct` storing its bandwidth estimation</span></div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span><span class="comment"> * variables).  Then when Westwood CC is enabled, its event handlers are set to Reno functions when classic SS</span></div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span><span class="comment"> * and CA are to be performed and to Westwood functions when a Westwood-specific action is to be performed</span></div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span><span class="comment"> * (set CWND to the bandwidth estimate * RTT-min).  It&#39;s hard to put into words, but while the idea is the</span></div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span><span class="comment"> * same, it&#39;s not really executed quite as cleanly as it could be.  The Linux-equivalent implementation in our</span></div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span><span class="comment"> * framework would be to have Congestion_control_classic store CWND and SSTHRESH and implement classic SS/CA</span></div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span><span class="comment"> * as well as CWND/SSTHRESH halving, then add Congestion_control_classic_with_bandwidth_est deriving from this</span></div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span><span class="comment"> * and try to alter the superclass&#39;s behavior through inheritance (CWND setting to bandwidth-based value).</span></div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="comment"> * Instead of forcing this IS-A relationship (as Linux kind of does), it seems cleaner and more flexible to</span></div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="comment"> * use a HAS-A relationship:  Congestion_control_classic HAS-A Congestion_control_classic_data (and reuses all</span></div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span><span class="comment"> * of its code, and adds SSTHRESH/CWND halving on loss); Congestion_control_classic_with_bandwidth_est HAS-A</span></div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="comment"> * Congestion_control_classic_data (and reuses all of its code, plus adds setting SSTHRESH/CWND to a</span></div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment"> * bandwidth-based value).</span></div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span><span class="comment"> *</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span><span class="comment"> * ### Documentation ###</span></div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment"> * Because this class explicitly implements Reno-style CWND growth, upon which any user class</span></div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span><span class="comment"> * must be able to rely exactly, this class is uncharacteristically white-boxy in terms of its API and API</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span><span class="comment"> * documentation.  Each method documents exactly what happens to CWND and SSTHRESH; and no CWND/SSTHRESH</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span><span class="comment"> * changes are allowed except as documented.</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span><span class="comment"> *</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><span class="comment"> * ### Thread safety ###</span></div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span><span class="comment"> * Same as Congestion_control_strategy.</span></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span><span class="comment"> */</span></div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html">   76</a></span><span class="keyword">class </span><a class="code hl_class" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html">Congestion_control_classic_data</a> :</div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span>  <span class="keyword">public</span> <a class="code hl_class" href="classflow_1_1log_1_1Log__context.html">log::Log_context</a>,</div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span>  <span class="keyword">private</span> boost::noncopyable</div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span>{</div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span>  <span class="comment">// Constructors/destructor.</span></div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span><span class="comment"></span> </div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span><span class="comment">   * Constructs object by setting up logging and saving a pointer to the containing Peer_socket,</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span><span class="comment">   * setting CWND to a reasonable initial value (also known as Initial Window or IW) per classic TCP RFCs,</span></div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span><span class="comment">   * and setting SSTHRESH to infinity (ditto).</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="comment">   *</span></div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span><span class="comment">   * @param logger_ptr</span></div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span><span class="comment">   *        The Logger implementation to use subsequently.</span></div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span><span class="comment">   * @param sock</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment">   *        The Peer_socket.</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment">   */</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span>  <span class="keyword">explicit</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a537fe6cb424b4e2591cc4673ed9ec8a1">Congestion_control_classic_data</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr, <a class="code hl_typedef" href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">Peer_socket::Const_ptr</a> sock);</div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span> </div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span><span class="comment"></span> </div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span><span class="comment">   * Return current stored CWND value in bytes.  This corresponds to</span></div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span><span class="comment">   * Congestion_control_strategy::congestion_window_bytes().</span></div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span><span class="comment">   *</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span><span class="comment">   * @return Ditto.</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span><span class="comment">   */</span></div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span>  <span class="keywordtype">size_t</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#adbda0ed3747b1eea62f4d790c37dbe46">congestion_window_bytes</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span><span class="comment"></span> </div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span><span class="comment">   * Return current stored SSTHRESH value in bytes.  When congestion_window_bytes() &gt;= this value,</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span><span class="comment">   * it grows according to congestion avoidance mode (linearly).  Otherwise it grows according to</span></div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment">   * slow start mode (exponentially).</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span><span class="comment">   *</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span><span class="comment">   * @return See above.  Infinity is `&quot;numeric_limits&lt;size_t&gt;::max()&quot;`.</span></div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span><span class="comment">   */</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span>  <span class="keywordtype">size_t</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a1ca80ab86d6289af0f3b2bf123edd627">slow_start_threshold_bytes</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span><span class="comment"></span> </div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span><span class="comment">   * The value to which the constructor set the stored CWND value (also known as Initial Window or IW).</span></div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span><span class="comment">   * This is provided, because some congestion control algorithms may want to manually set CWND back</span></div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span><span class="comment">   * to this value on events like Idle Timeout.</span></div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span><span class="comment">   *</span></div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span><span class="comment">   */</span></div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span>  <span class="keywordtype">size_t</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#acaa476e1821e7ed1344de8c5bfc0c9a7">init_congestion_window_bytes</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span><span class="comment"></span> </div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span><span class="comment">   * Adjusts state, including potentially CWND, based on either &quot;congestion avoidance&quot; or &quot;slow</span></div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span><span class="comment">   * start&quot; algorithm, given that packets with the given amount of data were just converted from</span></div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span><span class="comment">   * In-flight to Acknowledged (i.e., were newly acknowledged).  CWND may change.  SSTHRESH will not</span></div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span><span class="comment">   * change.</span></div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span><span class="comment">   *</span></div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span><span class="comment">   * Specifically: If CWND &lt; SSTHRESH, then each byte of acked data causes CWND to increase by that</span></div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span><span class="comment">   * many bytes.  If CWND &gt;= SSTHRESH, then each CWND bytes of acked data causes CWND to be</span></div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span><span class="comment">   * increased by N * max-block-size bytes (in max-block-size-at-a-time increments), where N</span></div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span><span class="comment">   * is configurable by socket options (N = 1 is the value mandated by RFC 5681).  State is</span></div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span><span class="comment">   * internally maintained to enable the latter to work.  This is inspired by the classic TCP</span></div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span><span class="comment">   * congestion control combined with Appropriate Byte Counting (ABC).</span></div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span><span class="comment">   *</span></div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span><span class="comment">   * @param bytes</span></div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span><span class="comment">   *        Same meaning as for Congestion_Congestion_control_strategy::on_acks().</span></div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span><span class="comment">   */</span></div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#ab3e34468efdf4d9e5b29eceb1fe84665">on_acks</a>(<span class="keywordtype">size_t</span> bytes);</div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span><span class="comment"></span> </div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span><span class="comment">   * Sets internally stored SSHTRESH and CWND to the given values; appropriately resets internal</span></div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span><span class="comment">   * state so that on_acks() CWND accounting will continue to work properly.  See details inside the</span></div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno">  144</span><span class="comment">   * method if needed, but basically since the value of (CWND &lt; SSTHRESH) may be changed by this</span></div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno">  145</span><span class="comment">   * assignment, we may move from congestion avoidance to slow start.  If CWND changes at all, then</span></div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span><span class="comment">   * a new congestion avoidance session begins if one is in progress.  On the other hand if neither</span></div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno">  147</span><span class="comment">   * is true, then congestion avoidance or slow start will continue undisturbed in the next</span></div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span><span class="comment">   * on_acks() call.</span></div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span><span class="comment">   *</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span><span class="comment">   * @param new_slow_start_thresh_bytes</span></div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span><span class="comment">   *        New value for SSHTRESH.  (May be unchanged.)</span></div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span><span class="comment">   * @param new_cong_wnd_bytes</span></div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno">  153</span><span class="comment">   *        New value for CWND.  (May be unchanged.)</span></div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span><span class="comment">   */</span></div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno">  155</span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a79e85a67e583b74cc414524d53650892">on_congestion_event</a>(<span class="keywordtype">size_t</span> new_slow_start_thresh_bytes, <span class="keywordtype">size_t</span> new_cong_wnd_bytes);</div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span><span class="comment"></span> </div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span><span class="comment">   * Adjust state, including CWND and SSTHRESH, assuming a Drop Timeout just occurred.</span></div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span><span class="comment">   * This is typically treated similarly in most (all?) congestion control strategies, so it is</span></div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span><span class="comment">   * factored out into a method.  (The caller can of course choose to perform additional steps</span></div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span><span class="comment">   * before or after.)  Both CWND and SSTHRESH will change.</span></div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span><span class="comment">   *</span></div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span><span class="comment">   * Specifically: Sets CWND to a low value, since Drop Timeout indicates a major loss event and</span></div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span><span class="comment">   * possibly major congestion; sets SSTHRESH to the given value (which is highly dependent on the</span></div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno">  165</span><span class="comment">   * caller congestion control strategy).  The CWND part is taken from classic TCP congestion</span></div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span><span class="comment">   * control.</span></div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span><span class="comment">   *</span></div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno">  168</span><span class="comment">   * Logging: logs the before/after states of the change, but caller is encouraged to explain what</span></div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span><span class="comment">   * it is about to do (e.g., halve SSTHRESH in case of classic Reno).</span></div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno">  170</span><span class="comment">   *</span></div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno">  171</span><span class="comment">   * @param new_slow_start_thresh_bytes</span></div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span><span class="comment">   *        New value for SSHTRESH.  (May be unchanged.)</span></div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno">  173</span><span class="comment">   */</span></div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a63316b5d9e9a27816b09bb52c464b588">on_drop_timeout</a>(<span class="keywordtype">size_t</span> new_slow_start_thresh_bytes);</div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span><span class="comment"></span> </div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno">  176</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno">  177</span><span class="comment">   * Adjust state, namely CWND, assuming an Idle Timeout just occurred.</span></div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span><span class="comment">   * This is typically treated similarly in most (all?) congestion control strategies, so it is</span></div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span><span class="comment">   * factored out into a method.  (The caller can of course choose to perform additional steps</span></div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno">  180</span><span class="comment">   * before or after.)  CWND will change.  SSTHRESH will not change.</span></div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span><span class="comment">   *</span></div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span><span class="comment">   * Specifically: Sets CWND to a low value (the initial window), thus in effect restarting the</span></div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span><span class="comment">   * connection (except SSTHRESH is left alone).  The policy is taken from classic TCP</span></div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno">  184</span><span class="comment">   * congestion control.</span></div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span><span class="comment">   *</span></div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno">  186</span><span class="comment">   * Logs fully.</span></div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span><span class="comment">   */</span></div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#afbe0609319f117e90074e1241abbba5c">on_idle_timeout</a>();</div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno">  189</span> </div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span><span class="keyword">private</span>:</div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span> </div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno">  192</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span><span class="comment"></span> </div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno">  194</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span><span class="comment">   * Return `true` if and only if CWND &lt; SSTHRESH.</span></div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span><span class="comment">   *</span></div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno">  197</span><span class="comment">   * @return Ditto.</span></div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno">  198</span><span class="comment">   */</span></div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span>  <span class="keywordtype">bool</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#aecb03f208c177ec3cbce5242f19efee0">in_slow_start</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span><span class="comment"></span> </div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno">  202</span><span class="comment">   * Helper that returns `true` if and only if the given CWND &lt; the given SSTHRESH.</span></div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno">  203</span><span class="comment">   *</span></div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span><span class="comment">   * @param cong_wnd_bytes</span></div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno">  205</span><span class="comment">   *        CWND.</span></div>
<div class="line"><a id="l00206" name="l00206"></a><span class="lineno">  206</span><span class="comment">   * @param slow_start_thresh_bytes</span></div>
<div class="line"><a id="l00207" name="l00207"></a><span class="lineno">  207</span><span class="comment">   *        SSTHRESH.</span></div>
<div class="line"><a id="l00208" name="l00208"></a><span class="lineno">  208</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00209" name="l00209"></a><span class="lineno">  209</span><span class="comment">   */</span></div>
<div class="line"><a id="l00210" name="l00210"></a><span class="lineno">  210</span>  <span class="keyword">static</span> <span class="keywordtype">bool</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#aecb03f208c177ec3cbce5242f19efee0">in_slow_start</a>(<span class="keywordtype">size_t</span> cong_wnd_bytes, <span class="keywordtype">size_t</span> slow_start_thresh_bytes);</div>
<div class="line"><a id="l00211" name="l00211"></a><span class="lineno">  211</span><span class="comment"></span> </div>
<div class="line"><a id="l00212" name="l00212"></a><span class="lineno">  212</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00213" name="l00213"></a><span class="lineno">  213</span><span class="comment">   * Returns `true` if and only if the stored CWND is &gt;= a certain constant maximum value.</span></div>
<div class="line"><a id="l00214" name="l00214"></a><span class="lineno">  214</span><span class="comment">   *</span></div>
<div class="line"><a id="l00215" name="l00215"></a><span class="lineno">  215</span><span class="comment">   * @return Ditto.</span></div>
<div class="line"><a id="l00216" name="l00216"></a><span class="lineno">  216</span><span class="comment">   */</span></div>
<div class="line"><a id="l00217" name="l00217"></a><span class="lineno">  217</span>  <span class="keywordtype">bool</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a9c6cac4d5409855f5e39f4411d787ad9">congestion_window_at_limit</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00218" name="l00218"></a><span class="lineno">  218</span><span class="comment"></span> </div>
<div class="line"><a id="l00219" name="l00219"></a><span class="lineno">  219</span><span class="comment">  /// If congestion_window_at_limit(), sets CWND to the limit value.</span></div>
<div class="line"><a id="l00220" name="l00220"></a><span class="lineno">  220</span><span class="comment"></span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a7b798f3211fd2214477355b95e2d10d2">clamp_congestion_window</a>();</div>
<div class="line"><a id="l00221" name="l00221"></a><span class="lineno">  221</span><span class="comment"></span> </div>
<div class="line"><a id="l00222" name="l00222"></a><span class="lineno">  222</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00223" name="l00223"></a><span class="lineno">  223</span><span class="comment">   * Logs, in a TRACE message, all internal state values.</span></div>
<div class="line"><a id="l00224" name="l00224"></a><span class="lineno">  224</span><span class="comment">   *</span></div>
<div class="line"><a id="l00225" name="l00225"></a><span class="lineno">  225</span><span class="comment">   * @param context</span></div>
<div class="line"><a id="l00226" name="l00226"></a><span class="lineno">  226</span><span class="comment">   *        A brief description of where the caller is.  Preferably this should be lower-case</span></div>
<div class="line"><a id="l00227" name="l00227"></a><span class="lineno">  227</span><span class="comment">   *        letters with dashes separating words.  We add this to the log message.  Example:</span></div>
<div class="line"><a id="l00228" name="l00228"></a><span class="lineno">  228</span><span class="comment">   *        `&quot;ack-before&quot;`.</span></div>
<div class="line"><a id="l00229" name="l00229"></a><span class="lineno">  229</span><span class="comment">   */</span></div>
<div class="line"><a id="l00230" name="l00230"></a><span class="lineno">  230</span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a092ddd8d1f700b426a5f9e0184af004f">log_state</a>(<span class="keyword">const</span> std::string&amp; context) <span class="keyword">const</span>;</div>
<div class="line"><a id="l00231" name="l00231"></a><span class="lineno">  231</span><span class="comment"></span> </div>
<div class="line"><a id="l00232" name="l00232"></a><span class="lineno">  232</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00233" name="l00233"></a><span class="lineno">  233</span><span class="comment">   * Analogous to Congestion_control_strategy::socket().</span></div>
<div class="line"><a id="l00234" name="l00234"></a><span class="lineno">  234</span><span class="comment">   *</span></div>
<div class="line"><a id="l00235" name="l00235"></a><span class="lineno">  235</span><span class="comment">   * @return Ditto.</span></div>
<div class="line"><a id="l00236" name="l00236"></a><span class="lineno">  236</span><span class="comment">   */</span></div>
<div class="line"><a id="l00237" name="l00237"></a><span class="lineno">  237</span>  <a class="code hl_typedef" href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">Peer_socket::Const_ptr</a> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a842fd11c65c3be53ce3d81a7f050f7d7">socket</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00238" name="l00238"></a><span class="lineno">  238</span> </div>
<div class="line"><a id="l00239" name="l00239"></a><span class="lineno">  239</span>  <span class="comment">// Constants.</span></div>
<div class="line"><a id="l00240" name="l00240"></a><span class="lineno">  240</span><span class="comment"></span> </div>
<div class="line"><a id="l00241" name="l00241"></a><span class="lineno">  241</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00242" name="l00242"></a><span class="lineno">  242</span><span class="comment">   * The constant that limits how much CWND can grow in slow start for a single ack group.  In</span></div>
<div class="line"><a id="l00243" name="l00243"></a><span class="lineno">  243</span><span class="comment">   * on_acks(), while in_slow_start(), each byte acknowledged increments CWND by 1 byte.  However,</span></div>
<div class="line"><a id="l00244" name="l00244"></a><span class="lineno">  244</span><span class="comment">   * if the total number of such bytes exceeds this constant, CWND only increments by this constant</span></div>
<div class="line"><a id="l00245" name="l00245"></a><span class="lineno">  245</span><span class="comment">   * times max-block-size.</span></div>
<div class="line"><a id="l00246" name="l00246"></a><span class="lineno">  246</span><span class="comment">   */</span></div>
<div class="line"><a id="l00247" name="l00247"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#ad5141d276b63528195d360f537cd4882">  247</a></span>  <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">size_t</span> <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#ad5141d276b63528195d360f537cd4882">S_MAX_SLOW_START_CWND_INCREMENT_BLOCKS</a>;</div>
<div class="line"><a id="l00248" name="l00248"></a><span class="lineno">  248</span> </div>
<div class="line"><a id="l00249" name="l00249"></a><span class="lineno">  249</span>  <span class="comment">// Data.</span></div>
<div class="line"><a id="l00250" name="l00250"></a><span class="lineno">  250</span><span class="comment"></span> </div>
<div class="line"><a id="l00251" name="l00251"></a><span class="lineno">  251</span><span class="comment">  /// Same meaning as in Congestion_control_strategy.</span></div>
<div class="line"><a id="l00252" name="l00252"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#ae8b85cd84e7e0496ad10814008fbd9fc">  252</a></span><span class="comment"></span>  boost::weak_ptr&lt;Peer_socket::Const_ptr::element_type&gt; <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#ae8b85cd84e7e0496ad10814008fbd9fc">m_sock</a>;</div>
<div class="line"><a id="l00253" name="l00253"></a><span class="lineno">  253</span><span class="comment"></span> </div>
<div class="line"><a id="l00254" name="l00254"></a><span class="lineno">  254</span><span class="comment">  /// Current value of CWND.</span></div>
<div class="line"><a id="l00255" name="l00255"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a2eb9570b7c5e58a732b05a19187c0fef">  255</a></span><span class="comment"></span>  <span class="keywordtype">size_t</span> <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a2eb9570b7c5e58a732b05a19187c0fef">m_cong_wnd_bytes</a>;</div>
<div class="line"><a id="l00256" name="l00256"></a><span class="lineno">  256</span><span class="comment"></span> </div>
<div class="line"><a id="l00257" name="l00257"></a><span class="lineno">  257</span><span class="comment">  /// Initial value of CWND in constructor.</span></div>
<div class="line"><a id="l00258" name="l00258"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a7c792d850821c8a7c711204db867089b">  258</a></span><span class="comment"></span>  <span class="keyword">const</span> <span class="keywordtype">size_t</span> <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a7c792d850821c8a7c711204db867089b">m_init_cong_wnd_bytes</a>;</div>
<div class="line"><a id="l00259" name="l00259"></a><span class="lineno">  259</span><span class="comment"></span> </div>
<div class="line"><a id="l00260" name="l00260"></a><span class="lineno">  260</span><span class="comment">  /// Current value of SSTRESH.</span></div>
<div class="line"><a id="l00261" name="l00261"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a239c6315ca562c4e782431879f39c74d">  261</a></span><span class="comment"></span>  <span class="keywordtype">size_t</span> <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a239c6315ca562c4e782431879f39c74d">m_slow_start_thresh_bytes</a>;</div>
<div class="line"><a id="l00262" name="l00262"></a><span class="lineno">  262</span><span class="comment"></span> </div>
<div class="line"><a id="l00263" name="l00263"></a><span class="lineno">  263</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00264" name="l00264"></a><span class="lineno">  264</span><span class="comment">   * While in congestion avoidance mode (`!in_slow_start()`), the # of acked bytes reported to</span></div>
<div class="line"><a id="l00265" name="l00265"></a><span class="lineno">  265</span><span class="comment">   * on_acks() that have not yet been accounted for in a CWND increase.  This corresponds to the</span></div>
<div class="line"><a id="l00266" name="l00266"></a><span class="lineno">  266</span><span class="comment">   * `bytes_acked` variable in TCP RFC 3465-2.1.  When in_slow_start(), this value is zero and unused.</span></div>
<div class="line"><a id="l00267" name="l00267"></a><span class="lineno">  267</span><span class="comment">   *</span></div>
<div class="line"><a id="l00268" name="l00268"></a><span class="lineno">  268</span><span class="comment">   * More formally, the congestion avoidance (CA) algorithm with Appropriate Byte Counting (ABC), as</span></div>
<div class="line"><a id="l00269" name="l00269"></a><span class="lineno">  269</span><span class="comment">   * implemented here, works as follows.  When CA is entered, #m_acked_bytes_since_window_update = 0.</span></div>
<div class="line"><a id="l00270" name="l00270"></a><span class="lineno">  270</span><span class="comment">   * Then, in every on_acks() call, it is incremented by `bytes`.  Once it exceeds CWND, CWND bytes</span></div>
<div class="line"><a id="l00271" name="l00271"></a><span class="lineno">  271</span><span class="comment">   * are &quot;converted&quot; into a CWND increase of N * max-block-size bytes, by performing said CWND increment</span></div>
<div class="line"><a id="l00272" name="l00272"></a><span class="lineno">  272</span><span class="comment">   * and subtracting the pre-increment CWND value from #m_acked_bytes_since_window_update.  The</span></div>
<div class="line"><a id="l00273" name="l00273"></a><span class="lineno">  273</span><span class="comment">   * remainder of this operation is less than CWND and is in #m_acked_bytes_since_window_update. The</span></div>
<div class="line"><a id="l00274" name="l00274"></a><span class="lineno">  274</span><span class="comment">   * latter is then incremented in the next on_acks(), and so on, until CA ends (something causes</span></div>
<div class="line"><a id="l00275" name="l00275"></a><span class="lineno">  275</span><span class="comment">   * in_slow_start()).</span></div>
<div class="line"><a id="l00276" name="l00276"></a><span class="lineno">  276</span><span class="comment">   */</span></div>
<div class="line"><a id="l00277" name="l00277"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a217f407429d1cf215177e3f49f86b6d6">  277</a></span>  <span class="keywordtype">size_t</span> <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a217f407429d1cf215177e3f49f86b6d6">m_acked_bytes_since_window_update</a>;</div>
<div class="line"><a id="l00278" name="l00278"></a><span class="lineno">  278</span>}; <span class="comment">// class Congestion_control_classic_data</span></div>
<div class="line"><a id="l00279" name="l00279"></a><span class="lineno">  279</span> </div>
<div class="line"><a id="l00280" name="l00280"></a><span class="lineno">  280</span>} <span class="comment">// namespace flow::net_flow</span></div>
<div class="ttc" id="aclassflow_1_1log_1_1Log__context_html"><div class="ttname"><a href="classflow_1_1log_1_1Log__context.html">flow::log::Log_context</a></div><div class="ttdoc">Convenience class that simply stores a Logger and/or Component passed into a constructor; and returns...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01609">log.hpp:1610</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Logger_html"><div class="ttname"><a href="classflow_1_1log_1_1Logger.html">flow::log::Logger</a></div><div class="ttdoc">Interface that the user should implement, passing the implementing Logger into logging classes (Flow'...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01280">log.hpp:1284</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html">flow::net_flow::Congestion_control_classic_data</a></div><div class="ttdoc">Utility class for use by Congestion_control_strategy implementations that implements congestion windo...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8hpp_source.html#l00076">cong_ctl_util.hpp:79</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a092ddd8d1f700b426a5f9e0184af004f"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a092ddd8d1f700b426a5f9e0184af004f">flow::net_flow::Congestion_control_classic_data::log_state</a></div><div class="ttdeci">void log_state(const std::string &amp;context) const</div><div class="ttdoc">Logs, in a TRACE message, all internal state values.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00375">cong_ctl_util.cpp:375</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a1ca80ab86d6289af0f3b2bf123edd627"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a1ca80ab86d6289af0f3b2bf123edd627">flow::net_flow::Congestion_control_classic_data::slow_start_threshold_bytes</a></div><div class="ttdeci">size_t slow_start_threshold_bytes() const</div><div class="ttdoc">Return current stored SSTHRESH value in bytes.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00071">cong_ctl_util.cpp:71</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a217f407429d1cf215177e3f49f86b6d6"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a217f407429d1cf215177e3f49f86b6d6">flow::net_flow::Congestion_control_classic_data::m_acked_bytes_since_window_update</a></div><div class="ttdeci">size_t m_acked_bytes_since_window_update</div><div class="ttdoc">While in congestion avoidance mode (!in_slow_start()), the # of acked bytes reported to on_acks() tha...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8hpp_source.html#l00277">cong_ctl_util.hpp:277</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a239c6315ca562c4e782431879f39c74d"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a239c6315ca562c4e782431879f39c74d">flow::net_flow::Congestion_control_classic_data::m_slow_start_thresh_bytes</a></div><div class="ttdeci">size_t m_slow_start_thresh_bytes</div><div class="ttdoc">Current value of SSTRESH.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8hpp_source.html#l00261">cong_ctl_util.hpp:261</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a2eb9570b7c5e58a732b05a19187c0fef"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a2eb9570b7c5e58a732b05a19187c0fef">flow::net_flow::Congestion_control_classic_data::m_cong_wnd_bytes</a></div><div class="ttdeci">size_t m_cong_wnd_bytes</div><div class="ttdoc">Current value of CWND.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8hpp_source.html#l00255">cong_ctl_util.hpp:255</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a537fe6cb424b4e2591cc4673ed9ec8a1"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a537fe6cb424b4e2591cc4673ed9ec8a1">flow::net_flow::Congestion_control_classic_data::Congestion_control_classic_data</a></div><div class="ttdeci">Congestion_control_classic_data(log::Logger *logger_ptr, Peer_socket::Const_ptr sock)</div><div class="ttdoc">Constructs object by setting up logging and saving a pointer to the containing Peer_socket,...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00033">cong_ctl_util.cpp:33</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a63316b5d9e9a27816b09bb52c464b588"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a63316b5d9e9a27816b09bb52c464b588">flow::net_flow::Congestion_control_classic_data::on_drop_timeout</a></div><div class="ttdeci">void on_drop_timeout(size_t new_slow_start_thresh_bytes)</div><div class="ttdoc">Adjust state, including CWND and SSTHRESH, assuming a Drop Timeout just occurred.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00293">cong_ctl_util.cpp:293</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a79e85a67e583b74cc414524d53650892"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a79e85a67e583b74cc414524d53650892">flow::net_flow::Congestion_control_classic_data::on_congestion_event</a></div><div class="ttdeci">void on_congestion_event(size_t new_slow_start_thresh_bytes, size_t new_cong_wnd_bytes)</div><div class="ttdoc">Sets internally stored SSHTRESH and CWND to the given values; appropriately resets internal state so ...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00228">cong_ctl_util.cpp:228</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a7b798f3211fd2214477355b95e2d10d2"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a7b798f3211fd2214477355b95e2d10d2">flow::net_flow::Congestion_control_classic_data::clamp_congestion_window</a></div><div class="ttdeci">void clamp_congestion_window()</div><div class="ttdoc">If congestion_window_at_limit(), sets CWND to the limit value.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00352">cong_ctl_util.cpp:352</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a7c792d850821c8a7c711204db867089b"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a7c792d850821c8a7c711204db867089b">flow::net_flow::Congestion_control_classic_data::m_init_cong_wnd_bytes</a></div><div class="ttdeci">const size_t m_init_cong_wnd_bytes</div><div class="ttdoc">Initial value of CWND in constructor.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8hpp_source.html#l00258">cong_ctl_util.hpp:258</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a842fd11c65c3be53ce3d81a7f050f7d7"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a842fd11c65c3be53ce3d81a7f050f7d7">flow::net_flow::Congestion_control_classic_data::socket</a></div><div class="ttdeci">Peer_socket::Const_ptr socket() const</div><div class="ttdoc">Analogous to Congestion_control_strategy::socket().</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00390">cong_ctl_util.cpp:390</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a9c6cac4d5409855f5e39f4411d787ad9"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a9c6cac4d5409855f5e39f4411d787ad9">flow::net_flow::Congestion_control_classic_data::congestion_window_at_limit</a></div><div class="ttdeci">bool congestion_window_at_limit() const</div><div class="ttdoc">Returns true if and only if the stored CWND is &gt;= a certain constant maximum value.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00345">cong_ctl_util.cpp:345</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_ab3e34468efdf4d9e5b29eceb1fe84665"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#ab3e34468efdf4d9e5b29eceb1fe84665">flow::net_flow::Congestion_control_classic_data::on_acks</a></div><div class="ttdeci">void on_acks(size_t bytes)</div><div class="ttdoc">Adjusts state, including potentially CWND, based on either &quot;congestion avoidance&quot; or &quot;slow start&quot; alg...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00076">cong_ctl_util.cpp:76</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_acaa476e1821e7ed1344de8c5bfc0c9a7"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#acaa476e1821e7ed1344de8c5bfc0c9a7">flow::net_flow::Congestion_control_classic_data::init_congestion_window_bytes</a></div><div class="ttdeci">size_t init_congestion_window_bytes() const</div><div class="ttdoc">The value to which the constructor set the stored CWND value (also known as Initial Window or IW).</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00066">cong_ctl_util.cpp:66</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_ad5141d276b63528195d360f537cd4882"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#ad5141d276b63528195d360f537cd4882">flow::net_flow::Congestion_control_classic_data::S_MAX_SLOW_START_CWND_INCREMENT_BLOCKS</a></div><div class="ttdeci">static const size_t S_MAX_SLOW_START_CWND_INCREMENT_BLOCKS</div><div class="ttdoc">The constant that limits how much CWND can grow in slow start for a single ack group.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8hpp_source.html#l00247">cong_ctl_util.hpp:247</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_adbda0ed3747b1eea62f4d790c37dbe46"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#adbda0ed3747b1eea62f4d790c37dbe46">flow::net_flow::Congestion_control_classic_data::congestion_window_bytes</a></div><div class="ttdeci">size_t congestion_window_bytes() const</div><div class="ttdoc">Return current stored CWND value in bytes.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00061">cong_ctl_util.cpp:61</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_ae8b85cd84e7e0496ad10814008fbd9fc"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#ae8b85cd84e7e0496ad10814008fbd9fc">flow::net_flow::Congestion_control_classic_data::m_sock</a></div><div class="ttdeci">boost::weak_ptr&lt; Peer_socket::Const_ptr::element_type &gt; m_sock</div><div class="ttdoc">Same meaning as in Congestion_control_strategy.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8hpp_source.html#l00252">cong_ctl_util.hpp:252</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_aecb03f208c177ec3cbce5242f19efee0"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#aecb03f208c177ec3cbce5242f19efee0">flow::net_flow::Congestion_control_classic_data::in_slow_start</a></div><div class="ttdeci">bool in_slow_start() const</div><div class="ttdoc">Return true if and only if CWND &lt; SSTHRESH.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00365">cong_ctl_util.cpp:365</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_afbe0609319f117e90074e1241abbba5c"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#afbe0609319f117e90074e1241abbba5c">flow::net_flow::Congestion_control_classic_data::on_idle_timeout</a></div><div class="ttdeci">void on_idle_timeout()</div><div class="ttdoc">Adjust state, namely CWND, assuming an Idle Timeout just occurred.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00312">cong_ctl_util.cpp:312</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Shared__ptr__alias__holder_html_aef7998db71c60eeb5d1e3d1a97c14886"><div class="ttname"><a href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">flow::util::Shared_ptr_alias_holder&lt; boost::shared_ptr&lt; Peer_socket &gt; &gt;::Const_ptr</a></div><div class="ttdeci">Const_target_ptr Const_ptr</div><div class="ttdoc">Short-hand for ref-counted pointer to immutable values of type Target_type::element_type (a-la T cons...</div><div class="ttdef"><b>Definition:</b> <a href="shared__ptr__alias__holder_8hpp_source.html#l00127">shared_ptr_alias_holder.hpp:127</a></div></div>
<div class="ttc" id="adetail_2net__flow__fwd_8hpp_html"><div class="ttname"><a href="detail_2net__flow__fwd_8hpp.html">net_flow_fwd.hpp</a></div></div>
<div class="ttc" id="anamespaceflow_1_1net__flow_html"><div class="ttname"><a href="namespaceflow_1_1net__flow.html">flow::net_flow</a></div><div class="ttdoc">Flow module containing the API and implementation of the Flow network protocol, a TCP-inspired stream...</div><div class="ttdef"><b>Definition:</b> <a href="asio_2node_8cpp_source.html#l00024">node.cpp:25</a></div></div>
<div class="ttc" id="apeer__socket_8hpp_html"><div class="ttname"><a href="peer__socket_8hpp.html">peer_socket.hpp</a></div></div>
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